1. Field of the Invention
The present invention relates to an image inspection device, an image inspection method and an image inspection program which perform inspection of an inspection target based on image data.
2. Description of Related Art
There has been an image measurement device capable of measuring a shape of a target based on image data obtained by capturing an image of the target (e.g., see JP H11-132740A, JP 2010-169584 A). In the image measurement device, for example, an image of a target placed on a stage is captured by an imaging device disposed above the stage. The shape of the target is measured based on image data obtained by imaging.
The shape of the target is measured using the image measurement device to determine whether or not the measurement result is within a permissible range (tolerance), thereby enabling inspection of the target.
In each of the image measurement devices described in JP 1111-132740 A and JP 2010-169584 A, the shape of the target is measured based on image data corresponding to a two-dimensional image.
Meanwhile, in recent years, an image measurement device of a triangular ranging system has been proposed. In the image measurement device of the triangular ranging system, the surface of a target placed on a stage is irradiated with light, and the reflected light is received by a light receiving element having one-dimensionally or two-dimensionally arranged pixels. The height of the surface of the target can be measured based on a peak position of a light reception amount distribution obtained by the light receiving element. This enables inspection of the height of the target as well.
Here, an area on the surface of the target, where the height is measurable by the image measurement device of the triangular ranging system, changes in accordance with a direction of the light with which the target is irradiated. For this reason, when a plurality of targets are placed on the stage in different positions and postures, there may occur variations in height-measurable area among the plurality of targets. Accordingly, if variations in actually measured portion occur among the plurality of targets, accurate inspection cannot be performed.